There are cases where data stored in a storage apparatus needs to be transferred to another storage apparatus. For example, in the case where an existing storage apparatus is replaced with a higher-performance storage apparatus, data transfer is carried out from the existing storage apparatus to the higher-performance storage apparatus. Such data transfer between storage apparatuses is referred to as data migration. In the case of carrying out data migration, for example, one of logical volumes in the storage apparatuses is specified as each of a transfer source and a transfer determination. The logical volumes are those logically provided in disk devices of the storage apparatuses.
In data migration, large quantities of data are transferred between storage apparatuses. Therefore, along with capacity enlargement of storage apparatuses, data migration tends to require a prolonged period of time. In view of such a problem, for example, a technique to reduce competition for physical resources at the time of parallel transfer between volumes has been proposed as data migration technology.
Japanese Laid-open Patent Application Publication No. 2008-108020
However, it is sometimes the case that the conventional technique for reducing competition for physical resources is not sufficient to promote processing efficiency for the entire data migration processing. For example, assume that there are variations in the number of logical volumes of individual disk devices, which logical volumes are data transfer units. In such a case, in only particular disk devices, multiple logical volumes may be left without being subjected to data transfer at the final stage of the data transfer. In this case, at the final stage of the data transfer, access concentration to the particular disk devices occurs, which reduces efficiency in data copy processing for the data transfer.